Oil refining



J. S. WALLIS Feb. 6, 1934.

on. REFINING Filed July 12, 1930 2 Sheets-Sheet l INVENTOR 4%Mum/d424,.- Y M 92;,

if: ATTORNEY if S. WALLIS OIL REFINING Filed July 12, 1930 2Sheets-Sheet 2 1 wii lNV NTOR d" /.14;

BY n

. 'J' ATTORNEY Patented Feb. 6, l34

UNHTED 2 S teaser PATENT @FFIQE Application July 12,, 1930. Serial No.467,499

3 Claims.

My invention relates to treatment of oil and more particularly tofractionating systems.

One phase of my invention comprisesa novel iractionating system whereina greater amount of 5 heat is abstracted from. the flue gases of heatersused for raising oil to fractionating or cracking temperature than hasheretofore been accomplished. In this phase of my invention I generatesteam by means of flue gases which have previously been used for theraising of temperature of oil, and this steam is used in the system, forexample, for operating the auxiliaries such as pumps.

In another phase of my invention I provide a novel combination of oilheater and steam generator capable of extracting a greater amount ofheat from products of combustion than previously known oil heaters.

The nature of the invention and other objects and the advantages thereofwillbecome apparent from a consideration of the following descriptiontaken in conjunction with the accompanying drawings constituting a partof this specification, of which:

Fig. 1 shows a fractionating system in accordance with the invention; II 4 Fig. 2 is a sectional view of my improved oil heater and steamgenerator taken on the line 2-2 of Fig. 3; and

Fig. 3 is a cross-sectional view taken on the line 33 of Fig. 2.

The system shown in Fig. 1 comprises an atmospheric fractionating tower10 and a vacuum tower 11. Heater 12 supplies heated oil through conduit13 to the atmospheric tower 10. This heater may be of the usual typehaving a bridge wall 14 behind which is a series of oil heating tubes15, and in the roof of which are radiant heat tubes 16, the tubes beingconnected in series. A supe'rheater may be included in the settingbehind the bridge wall as indicated at'1'7.

Tower 10 contains the usual bubble trays 18 and stripping sections 19.The heated oil, which is partially vaporized, is admitted into the towerbehind a baflie 20. Vapor leaves the top of the tower through theconduit 21, passes through a heat exchanger 22 and a condenser 23 and isin part returned to the tower as liquid through conduit 24 by means ofreflux pump 25. Side streams are taken ofi from the tower at 27. Steamis introduced into the tower by means of conduits 28. Bottoms from tower10 pass through conduit 29 and bottoms pump 30 into heater 31. In heater31 the oilpasses through tubes 32 behind the bridge wall 33 and thencethrough roof tubes 34,

and thence through conduit 35 into tower 11 behind baflie 36.

Tower 11 also contains bubble trays 18 and stripping sections 19. Sidestreams are also withdrawn as at 27. Vapors are withdrawn from the towerthrough conduit 38, pass through a heat exchanger 39 and to a surfacecondenser 40; in

' which the oil vapors are condensed, the oil passing by gravity throughconduit41 to run-down tank 42 and stream passing through conduit 43 tobaro-' c5 metric condenser 44. Some of the oil is refluxed from run-downtank 42 through conduit 45,,in which is inserted reflux pump 46. Pumps47, 48, 49 and 50 pump oil from the vacuum run-down tanks 42, 51, 52 and53 to storage or other point of reception. The vacuum run-down tanks 51,,52 and 53 are connected to the side stream con duits 2'7. There may beany number of side streams takenirom the towers. Bottoms are withdrawnfrom the vacuum tower 11 through conduit 53' and pumped, by means ofpumps 54,-

to storage or use. Oil is supplied to the system by means of pipe 76 andis pumped by pump 75 first through heat exchanger 22, thence throughheat exchanger 39, thence through heat ex- 30 changers in various sidestream conduits, and thence into heater 12.

Incorporated in the setting of heater 31 is a steam generatordiagrammatically illustrated in Fig. 1 and indicated generally byreference char- 8 actor 56. The steam generator comprises a. steam andwater drum 57. Water is fed to the steam generator by means of conduit58 and through feed water heater 59 which is situated in the path offlow of the products of combustion behind the bridge wall 33. Athermosyphon circuit 60 comprises a conduit extending downwardly from.the steam and water drum 57 and conduits connected theretoin the heatersetting behind the bridge wall and arranged to be contacted bytheproducts of combustion and a conduit connecting these tubes with thesteam and water drum. Steam is withdrawn fromthe top of the steam andwater drum 5'7 and passes through superheater 61, which is also behindthe bridge wall and arranged to be heated by the products of combustion,and thence through conduit 62.

I use the steam produced in the steam generator 56 to operate variouspumps. A conduit 63 0011- ducts steam to pump 30, or, more accurately,to the steam motor for driving pump 30. A branch conduit 64 conductssteam from conduit 62 to the motor for running pump 25. All the variousmotors are designated by the reference character 65. Conduit 62 isconnected to a conduit 66, from which branch pipes 67, 68, 69, 70, '71,'72, '13 and 74 lead to the motors for operating pumps '75, 46, 47, 48,49, 5c and 54 respectively.

lf desired, some of the steam may be supplied to other consumers asindicated at 79. If the steam developed by the steam generator 56 is notsufiicient for the various auxiliaries additional steam may be suppliedthrough conduit 80.

The steam, after passing through motors 65,

passes through conduits 81 and'into a conduit 82 which supplies steam tothe stripping sections of the vacuum tower. If desired, this steam maybe superheated in a superheatcr 83 which may be incorporated in theheater 31.

The exhaust steam from the motors may also be introduced into tower 10.I have indicated this by showing the pipe 81 connected to the inlet ofsuperheater 17 and heater 12. Suitable valves are to be used in thevarious conduits to take care of flows and pressures.

It will be seen that the condensers 39 and 44 and the ejector 87 avacuum in the tower 11. This vacuum is communicated back through conduit82, which supplies steam to this tower, and thusthe exhausts of themotors for driving the auxiliaries is caused to be at lowpressure due tothe same apparatus which. produces the vacuum in the tower.

By incorporating the steam generator in the setting of heater 2-1 1 amable to reduce the flue gas temperature at the exit from the heater byseveral hundred degrees over what would be possible without the use of asteam generator in the setting. This means that there is a saving inrespect of the fuel used for raising the tempera ture of the oil,inasmuch as I utilize the steam produced in the steam generator fordriving the steam-driven pumps of the system and thereby save theintroduction of more or less steam into the system from another sourcefor driving these pumps. The system as a whole therefore, coop crates toreduce the amount of heat necessary to obtain the ultimate products offractionation.

In certain cases there is some difficulty in vaporizing the heavy oilextracted from the bottom of, for example, an atmospheric tower forfurther treatment in a vacuum tower. This vaporization can be assistedby the introduction of steam into the inter-stage heater, because by theintroduction of steam the partial pressure of the oil is lowered and ittherefore has a lower boiling point. To accomplish this I simply providea branch conduit 90 connecting conduit 62 with the inlet to the oilheating tubes 32 of heater 31. Some of the steam may be passed throughconduit 90 from the superheater 61 into the oil heating tubes of heater31. The control of this steam may be accomplished by means of a handvalve in conduit 90.

While it will be apparent that various kinds of combined steamgenerators and oil heaters may be employed, so far as the system as awhole is concerned, I have shown as one phase of my invention, in Figs.2 and 3, a structure which I consider particularly suitable for thepurpose set -also at a relatively low temperature, giving a highefficiency for heater 12. The reduced crude from tower 10 leaves at arelatively high temperature (500 F.). Therefore the charging stock willenter the oil surface of heater 31 at relatively high temperature (500F.) and the products of combustion leaving the oil heating surface ofheater 31 will be of a high temperature, say 700 F. or higher. If thiswere the final exhaust temperature, the heating for the second stagewould be inefficient. Consequently, my invention is particularlyapplicable to plants having fundamentally a high exit flue gastemperature from the oil surface.

The heater of Figs. 2 and 3 comprises walls 100 forming a setting.Extending upwardly from the base of the heater is a bridge wall 101which terminates short of the roof 102 and which divides the settinginto a combustion chamber 103 and a heating chamber 104. A burner 105 ofthe usual type supplies the fuel for combustion.

Behind the bridge wall and within the chamber 10% and near the top ofthe bridge wall is a series of oil conveying tubes 106, two rows beingshown. This group of tubes may be termed the convection group since itis heamd by convection. The tubes are connected in series, the oilpassing in at 10'? through the tubes of the lower row and thence throughthe tubes of the upper row. From the upper row of this group oil passesthrough a connection 108 to the roof tubes 1&9. The roof tubes may beconnected so that the oil passes either through the upper or lower tubesfirst and thence through the other. The tubes in each row are connectedby connections 110. The heated and vaporized oil. leaves the heaterthrough conduit 111 to pass to the tower such as tower 1G or 11 ofFig. 1. The roof tubes, which are radiant tubes, being heated by radiantheat, are bare tubes as contrasted tothe convection tubes, which arepreferably encased in cast iron extended. surface members 112. This typeof extended surface is well known per se. Below the convection group inchamber 104 are the heat absorbing tubes or the steam generator. Therearethree groups-of these tubes, the feed heater group 113, the boiler orthermo-syphon group 114, and the superheater group 115. Feed water issupplied through connection 116 and thence passes through the horizontaltubes of the feed water section 113. These tubes are connected instaggered relation as shown in Fig. 3. The tubes may be connected eitherin series in the same row with the rows in series, or in series first asto one row and then the other as shown in the drawings. The water, afterpassing through the feed water heating section, passes through conduit117 anzl into the steam and water drum 118, which is situated outsidethe boiler setting and at a higher level than the boiler tubes 114.Water flows downwardly through pipe 119 from the steam and water drumand passes into a manifold 120 wherefrom it is distributed to the tubesof the lowermost horizontal row of the group 114. The tubes of thelowermost row. are connected in series with adjacent tubes of the nextlowest row. The various tubes of any row are connected in parallel andthe rows are connected in series. Steam and water pass upwardly throughconduit 121 and back to the steam and water drum. Circulation isproduced due to the heating of the tubes 114. All the tubes of groups113, 114 and 115 are encased in corrosion resisting extended surfacematerial such as cast iron. Circulation is produced through the tubes114 due to the thermo-syphon action produced by the heating of thesetubes. This circulation is produced upwardly in the thermo-syphonsection 114, upwardly in conduit 121 and. downwardly in conduit 119,although the tubes lid are in a hori= zontal position. The side walls ofthis chamber are made up of plates, either solid or sectional izedplates. and the ends of the tubes extend through the plates. Theconnections between the tubes are outside the plates and therefore outof contact with respect to the hue gases. It is thus seen that the steamgenerator is very erficiently designed for resisting corrosive effectsof low temperature flue gases.

Steam leaves the upper part of the drum 118 and passes through conduit123 and into the superheater section 115. The steam passes out throughconduit 12% to the various motors as de-= scribed in connection withFig. 1. A connection 125, containing a hand valve 126, serves to permitsteam to pass into the oil heating section of the heater to assist inthe vaporization of the oil. The flue gases flow upwardly in chamber 103and downwardly in chamber 104 and thence to any suitable outlet such asa stack. It will be seen that the coldest heat absorbingmedium, namely,the cold feed water, is in contact with the end of the path of now orthe products of combustion, which is conducive to the highestefiiciency.

The side walls or plates of chamber 104 may be made of cast iron or maybe made of such heavy steel plate that they will stand up for a longperiod. The corrosive action of products of combustion, resulting fromthe burning of the fuel usually used for heating oil, is of a seriousnature. This has been observed in connection with air preheaters used tosave heat in such flue gases. It will become apparent that by the use ofa steam generator, and particularly the steam generator which I haveproposed, the problem of corrosion is taken ,careof, because cast ironsurfaces can be used, and cast iron is relatively non-corrosive.

In order to vary the amount of heating of the steam generatorindependently of the heating supplied by burner 105, I have provided anauxiliary combustion chamber 130, heated by an auxiliary burner 131. Theproducts of combustion pass from chamber 130 through flue 132 andbranches 133 and 134 to the convection chamber 104 ahead of thesuperheater section 115 and the boiler section 114 respectively. Dampers135 and 136 are providedin the branches 133 and 134, whereby the degreeof heating with respect to the difierent parts can be regulated at will.

While I have. described certain features more or less in detail and agiven system it will be understood that the invention may be embodied inother systems and that the invention is not limited to this specificapparatus described. It will be understood that the invention may beutilized in cracking processes as well as in fractionating processes.The scope of the invention is not to be limited except by the appendedclaims taken in connection with the state of the prior art.

What I claim is:

1. A combined oil heater and steam generator comprising walls forming asetting and means within said setting providing a path of flow ofproducts of combustion, an oil heating section in said path of flow anda steam generating section in said path of flow, the aforesaid sectionsbeing arranged in the path of flow so that the products of combustionfirst contact the oil heating section and then contact the steamgenerating section; said steam generating section comprising a pluralityof horizontal rows of tubes, a steam and water drum, means connectingsaid tubes with said drum to produce thermo-syphon circulation uponheating of said tubes by the products of. combustion, a feed watersection in said path of how behind said tubes section and a superheatersection in said path of flow ahead of the said tubes.-

2. Fluid heating apparatus comprising a furnace chamber and a tubechamber, a group of oil heating tubes inthe tube chamber, a group ofwater heating tubes, a group of steam generating tubes and a group ofsteam superheating tubes in the tube chamber, a steam and water drum,said groups of tubes being disposed in the tube chamber so that thestream of hot gases from the furnace chamber comes into contact firstwith the oil heating tubes, then with the steam superheatioo ing tubes,then with the steam generating tubes and finally with the water heatingtubes, means for forcing water through the water heating tubes and intosaid drum, conduits connecting the inlet and outlet of the group ofsteam generating tubes 1% and said drum to cause thermo-siphoncirculation through the steam generating tubes, a conduit for conductingsteam from said drum. through thesuperheating tubes, means for forcingoil through the oil heating tubes and means for varying thetemperatureand quantity of the hot gases in zones intermediate tubegroups.

3. Fluid heating apparatus comprising a furnace chamber and a tubechamber, a group of oil heating tubes in the tube chamber, a group ofwater heating tubes, a group of steam generating tubes and a group ofsteam superheating tubes in the tube chamber, a steam and water drum,said groups of tubes being disposed in the tube ,sei.

chamber so that the stream of hot gases from 120.

the furnace chamber comes into contact first with the oil heating tubes,then with the steam superheating tubes, then with the steam generatingtubes and finally with the water heating tubes, means for forcing waterthrough the water heating tubes and into said drum, conduits connecting,the inlet and outlet of the group of steam generating tubes and saiddrum to cause thermosiphon circulation through the steam generatingtubes, a conduit for conducting steam from said drum through thesuperheating tubes, a connection between the steam superheating tubesand the oil heating tubes whereby steam may be introduced into the oilflowing through the oil heating tubes, means for forcing oil through theoil heating tubes and means for varying the temperature and quantity ofthe hot gases in zones intermediate tube groups.

JOHN SAMUEL WALLIS. MG

